These faults do not necessarily occur instantaneously, they may develop over time leading to a gradual deterioration of the spark output. replacement for the condenser (capacitor) in As the size of the combustion chamber determines the time to burn the fuel charge, dual ignition was especially important for the large-bore aircraft engines around World War II where it was necessary to combust the entire fuel mixture in a shorter time than a single plug could provide, in order to build peak cylinder pressure at the rpm desired. So, re-check everything in the contact-breaker assembly first before deciding on a more complete overhaul. We would recommend having the transformer coil rewound as modern class F or H wires and insulations are superior to the ones used at the time it was originally made and would almost certainly give you another 40 years of good service. The voltage generated in the primary winding is a product of its velocity through the magnetic field and the strength of that field, so the condition of the magnet is vital for the correct performance of the magneto. That then produces a gap of about 4 mm between the centre electrode and the screw-threaded bit of the plug body. [6], The first car to use magneto ignition was the 1901 German Mercedes 35 hp racing car, followed by various cars produced by Benz, Mors, Turcat-Mery, and Nesseldorf. In this series of pages, well take you through the main things. Mechanical - Bearings, insulation, washers and shimming the armature. wish to 'demystify and simplify' wherever we can, so As the points begin to open, point spacing is initially such that the voltage across the primary coil would arc across the points. dynamos, regulators, alternators and I purchased this Lister D petrol (gasoline) engine that came on a trolley with an Aerograph air compressor. The points surfaces should be very slightly convex, so dont worry about getting them perfectly flat. We Magneto: No Spark - Antique Automobile Club of America However, provided the reading is more than about 500 ohms, it is probably OK. and just how were you able to find one of those bastards that still worked?!?!?! I highly doubt it is excessive unless someone has been grinding the rotor or the cap. If you are having trouble with your ignition system we recommend that you first change your spark plugs and HT leads. "Specializing in Triumph and other fine Vintage motorcycles". Then measure the resistance between the two points of the contact-breaker. Disassemble the advance/retard mechanism carefully noting which part goes where. Lucas KF2 magneto failure - Britbike forum Rotate the armature and check that, when the points are fully open, the moving point assembly is not fouling anything. startxref I was hoping that some of the experts might help me with a magneto problem. What else could possibly be grounding this? BTH mags utilized condensers made from mica. This dissipates the energy that was stored in the condenser in time for the next closure of the points, leaving the condenser discharged and ready to repeat the cycle. Check the condition of the HT lead(s) and plug-cap(s) and replace where necessary. Brightspark Magnetos Ltd disclaims responsibility for any The voltage generated across magneto coils is quite high, in the order of 20,000 volt if no spark plugs are in place. performance. 0000007301 00000 n We always replace the capacitor during a repair as experience has show us that the capacitor tends to be the most unreliable part. Undo the contact-breaker centre-screw and remove the contact-breaker assembly. Another cause of atom disorientation is mechanical shock, hammer blows or dropping the unit onto a hard surface, etc. Also, some pattern contact-breaker assemblies are too large at the fat end and need to be filed or ground to size. Do not skimp on quality with pick-up brushes. If the magnet is full strength and the spark at the points looks right then I would still say you have a coil problem with some shorted turns or something. Checked it over and found no spark. With the mag on the engine, there is a spark at all 4 plugs . 0000003777 00000 n magneto electronic ignition conversion, repairs Lucas & BTH, 5 year I know a great starting engine will fire a plug with 3/16" gap when external of a cylinder. There is no wire hooked up to the cap. Check for any dirty marks on the paper. This disables the magneto to reduce the risk of electric shock and fire. (Japanese) Just to reinforce a point here of something very well done that you did in the how-to: when you're testing a mag like this, ALWAYS have the plug wires hooked up with a gap (or plugs) to ground so that energy has somewhere to go. This is really common on original units as the Lucas condensers were made from wax paper and foil. If I was working on it, first I would want a 5/16" air gap consistent spark minimum from the coil terminal to ground. Norsk From the basic to the complex - some Any suggestions? A simple magneto (an electrical generator using permanent magnets) is able to produce relatively low voltage electricity, however it is unable to produce the high voltages required by a spark plug as used in most modern engines (aside from diesel engines). I also want to wire up the battery better, as I'm just using jumper cables. I'll try the 3/16" gap test. Capacitors, which are short-term storage devices, often fail in older magnetos due to dielectric degradation (short circuit) or conductor breakage (open circuit). how they work; and to collate as much other Fit the magneto gear to the magneto shaft and finger tighten the nut ONLY until the gear is snug on the tapered shaft. To have the discharge go arc back into the coil itself or the mag housing causes some serious damage. Any high tension magneto will have way more than 7 ohms resistance on the secondary circuit. Are suppressors and resistor sparking plugs OK to use with magnetos? If possible, get somebody to help. Check that all the insulators are in good shape, and reassemble the contact breaker assembly. Click on a button to see magnetos from other manufacturers Bosch BTH Others Click on any picture to get a larger view Rotate the armature until the contact-breaker points are open. making your own bearing and slip-ring pullers; An ignition magneto (also called a high-tension magneto) is an older type of ignition system used in spark-ignition engines (such as petrol engines). the brush spring is not touching the terminal in the pick-up holder; the connection between the cable and the pick-up is corroded; the screw in the plug cap has gone down the side of the HT cable and not down its centre; Slip-ring detailed guide to maintaining and In a modern installation, the magneto only has a single low tension winding which is connected to an external ignition coil which not only has a low tension winding, but also a secondary winding of many thousands of turns to deliver the high voltage required for the spark plug(s). Thanks again. Check the cam surface. MochetVelo Check the state of the contact return spring and replace if broken. I worked on farm equipment for my last real service job from 2013 thru 2016. 0000001320 00000 n The Fora platform includes forum software by XenForo. degrade with age. 1. If your magneto does not have an EasyCap but it fitted with a condenser buried in the armature, then it is impossible to check the condition of the condenser, while the armature is assembled, without specialised equipment. not load correctly in the translated versions of the pages. On more advanced magnetos the cam ring can be rotated by an external linkage to alter the ignition timing. It is also used in modern piston-engined aircraft[citation needed] (even though a battery is present), to avoid the engine relying on an electrical system. PA. insulators; and timing discs. 5.5 mm (220 thou) THREE-POINT SPARK GAP. It uses a magneto and a transformer to make pulses of high voltage for the spark plugs. If there are any, replace the pick-up. In either case, the magneto needs a more complete overhaul. Two beveled teeth on drive gear(which are generally parallel to flat for shaft it fits on) should go to mark on rotor which is under lead out finger. Re-install the contact-breaker assembly, ensuring that it registers properly with the armature shaft. If your multimeter can measure capacitance, the reading should be within 10% of: 150 nF (0.15 uF) for the C01, C02, C03, C05 and CU/150 EasyCaps; 220 nF (0.22 uF) for the C06, C07 and CU/220 EasyCaps. Our preferred gap for spark testing in fresh air is 6 mm. Having set the timing with the points opening on one cam lobe, you should check that it is also correct with the points opening on the other cam lobe. We would therefore strongly advise against ever trying to make a magneto strike a spark across a gap of anything in excess of 7.5 mm in fresh air. The place to buy our EasyCap condensers So I'm having an issue that is frustrating me and my mag rebuilder. For example: Check as best you can that the brush is actually making contact with the track on which it runs. And a f-ing video! With a multimeter, check the resistance between the brass of the slip ring and the end of the armature shaft (armature earth). With the points fully open, adjust the points gap to 0.012 (0.3 mm). <]>> We shall resume operations as soon as we possibly can. On the very first BSA I ever owned, I sufferred the same problem. 0000002602 00000 n Translate service. Free access to service and repair Post in the forum instead. Thorspark magneto ignition repair FAQ - Sussex motorcycles With twin- or multi-cylinder magnetos, and some single-cylinder magnetos, the brass is a segment, rather than a complete ring, and you may need to rotate the armature in order to be able to see it. However, typical signs of magneto problems are, among others: -- Bike hard to start. Trademark Office. For a better experience, please enable JavaScript in your browser before proceeding. Check out our magneto armature winding service. classic vehicles generally. Our I have tried both Champion and NGK plugs. We shall resume operations as soon as we possibly can. quality are also available, of the correct JRC Engineering Inc. 3110 Indian Ave Unit 1E, Perris, CA, 92571. MAGNETO MAGIC - PressReader BTH mags utilized condensers made from mica. It shouldnt be very many ohms, and certainly less than 30 ohms. At least I assume so: My timing light (seen in photo clamped to plug wire #1) illuminates correctly when plug #1 is unscrewed from the engine and sparks, but it does not light up when the plug is screwed into the engine. We recommend using non-resistive (copper) cable and unsuppressed plug caps. 0000004414 00000 n have a small choice of reconditioned Over time the HT leads can degrade and reduce the potential difference at the spark plug. I got it back, spun it, sparked. that old problem, the deeply-buried condenser A 0000005952 00000 n In the case of a main-body earth brush, try moistening a cotton bud with petrol, and poke it through the hole for the earth brush to clean the track while rotating the armature, but IMPORTANTLY before doing that temporarily remove or disable the contact breaker to reduce the risk of electric shock and fire. Svensk Remove the cam, carefully noting which way round it goes and which notches in it engage where. Turn the armature in its proper direction of rotation until the contact-breaker points are just starting to open on one of the cam lobes. pouvons vous aider soit en franais, soit en Nous This was examined earlier. use in our workshop for magneto servicing If you do not obtain readings substantially the same as the reading you obtained in the internal HT continuity section, and if everything else you previously checked is still good, it indicates that the pick-up brush(es) is/are not making good electrical contact with the brass of the slip ring. Due to the inevitable losses in the system, this oscillation decays fairly rapidly. I'm working on a Lucas Mag right now for the first time and this is extremely helpful. Lucasworkshopinstructions-magnetosLucasworkshopinstructions-otherstuffLucaspartslistsLucasATDspecificationsBTHinstructions&partslistsM-LBookletsMagntoFrancedocumentationRobertBoschDocumentationAmericanBoschworkshopinstructionsPatentsBooksandlearndpapers, Redesigned contact breaker for ring cam models, SR1, SR2 & SR4 magnetos (workshop Lister D Magneto Lucas RS1 full rebuild but still no spark - YouTube Remove the pick-up(s) from the magneto taking care not to mislay the gasket(s). Can you rig up real cables? Lucasworkshopinstructions-otherstuff. Also, with the points open, check that there is an open circuit between them; if fitted with a Brightspark EasyCap, it will take a little while for the resistance reading to climb off the scale. Twin sparks provide two flame fronts within the cylinder, these two flame fronts decreasing the time needed for the fuel charge to burn. Lucas SR2 Magneto - Hitchcocks Forum You are using an out of date browser. After a series of checks, I sent it back to the rebuilder. You need to confirm that the condenser has failed AND that replacing it will solve the problem.